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Purpose: Imaging Cherenkov light during radiotherapy allows the visualization and recording of frame‐by‐frame relative maps of the dose being delivered to the tissue at each control point used throughout treatment, providing one of the most complete real‐time means of treatment quality assurance. In non‐turbid media, the intensity of Cherenkov light is linear with surface dose deposited, however the emission from patient tissue is well‐known to be reduced by absorbing tissue components such as hemoglobin, fat, water, and melanin, and diffused by the scattering components of tissue. Earlier studies have shown that bulk correction could be achieved by using the patient planning computed tomography (CT) scan for attenuation correction. Methods: In this study, CT maps were used for correction of spatial variations in emissivity. Testing was completed on Cherenkov images from radiotherapy treatments of post‐lumpectomy breast cancer patients (n = 13), combined with spatial renderings of the patient radiodensity (CT number) from their planning CT scan. Results: The correction technique was shown to provide a pixel‐by‐pixel correction that suppressed many of the inter‐ and intra‐patient differences in the Cherenkov light emitted per unit dose. This correction was established from a calibration curve that correlated Cherenkov light intensity to surface‐rendered CT number (R6MV2=0.70$R_{6{\rm{MV}}}^2 = 0.70$ and R10MV2=0.72$R_{10{\rm{MV}}}^2 = 0.72$). The corrected Cherenkov intensity per unit dose standard error was reduced by nearly half (from ∼30% to ∼17%). Conclusions: This approach provides evidence that the planning CT scan can mitigate some of the tissue‐specific attenuation in Cherenkov images, allowing them to be translated into near surface dose images. [ABSTRACT FROM AUTHOR]

Purpose: The novel scintillator‐based system described in this study is capable of accurately and remotely measuring surface dose during Total Skin Electron Therapy (TSET); this dosimeter does not require post‐exposure processing or annealing and has been shown to be re‐usable, resistant to radiation damage, have minimal impact on surface dose, and reduce chances of operator error compared to existing technologies e.g. optically stimulated luminescence detector (OSLD). The purpose of this study was to quantitatively analyze the workflow required to measure surface dose using this new scintillator dosimeter and compare it to that of standard OSLDs. Methods: Disc‐shaped scintillators were attached to a flat‐faced phantom and a patient undergoing TSET. Light emission from these plastic discs was captured using a time‐gated, intensified, camera during irradiation and converted to dose using an external calibration factor. Time required to complete each step (daily QA, dosimeter preparation, attachment, removal, registration, and readout) of the scintillator and OSLD surface dosimetry workflows was tracked. Results: In phantoms, scintillators and OSLDs surface doses agreed within 3% for all data points. During patient imaging it was found that surface dose measured by OSLD and scintillator agreed within 5% and 3% for 35/35 and 32/35 dosimetry sites, respectively. The end‐to‐end time required to measure surface dose during phantom experiments for a single dosimeter was 78 and 202 sec for scintillator and OSL dosimeters, respectively. During patient treatment, surface dose was assessed at 7 different body locations by scintillator and OSL dosimeters in 386 and 754 sec, respectively. Conclusion: Scintillators have been shown to report dose nearly twice as fast as OSLDs with substantially less manual work and reduced chances of human error. Scintillator dose measurements are automatically saved to an electronic patient file and images contain a permanent record of the dose delivered during treatment. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to create an optical imaging‐based system for quality assurance (QA) testing of a dedicated Co‐60 total body irradiation (TBI) machine. Our goal is to streamline the QA process by minimizing the amount time necessary for tests such as verification of dose rate and field homogeneity. Methods: Plastic scintillating rods were placed directly on the patient treatment couch of a dedicated TBI 60Co irradiator. A tripod‐mounted intensified camera was placed directly adjacent to the couch. Images were acquired over a 30‐s period once the cobalt source was fully exposed. Real‐time image filtering was used; cumulative images were flatfield corrected as well as background and darkfield subtracted. Scintillators were used to measure light‐radiation field correspondence, dose rate, field homogeneity, and symmetry. Dose rate effects were measured by modifying the height of the treatment couch and scintillator response was compared to ionization chamber (IC) measurements. Optically stimulated luminesce detector (OSLD) used as reference dosimeters during field symmetry and homogeneity testing. Results: The scintillator‐based system accurately reported changes in dose rate. When comparing normalized output values for IC vs scintillators over a range of source‐to‐surface distances, a linear relationship (R2 = 0.99) was observed. Normalized scintillator signal matched OSLD measurements with <1.5% difference during field homogeneity and symmetry testing. Beam symmetry across both axes of the field was within 2%. The light field was found to correspond to 90 ± 3% of the isodose maximum along the longitudinal and latitudinal axis, respectively. Scintillator imaging output results using a single image stack requiring no postexposure processing (needed for OSLD) or repeat manual measurements (needed for IC). Conclusion: Imaging of scintillation light emission from plastic rods is a viable and efficient method for carrying out TBI 60Co irradiator QA. We have shown that this technique can accurately measure field homogeneity, symmetry, light‐radiation field correspondence, and dose rate effects. [ABSTRACT FROM AUTHOR]

Purpose: A remote imaging system tracking Cherenkov emission was analyzed to verify that the linear accelerator (linac) beam shape could be quantitatively measured at the irradiation surface for Quality Audit (QA). Methods: The Cherenkov camera recorded 2D dose images delivered on a solid acrylonitrile butadiene styrene (ABS) plastic phantom surface for a range of square beam sizes, and 6 MV photons. Imaging was done at source to surface distance (SSD) of 100 cm and compared to GaF film images and linac light fields of the same beam sizes, ranging over 5 × 5 cm2 up to 20 × 20 cm2. Line profiles of each field were compared in both X and Y jaw directions. Each measurement was repeated on two different Clinac2100 machines. An interreader comparison of the beam width interpretation was completed using procedures commonly employed for beam to light field coincidence verification. Cherenkov measurements are also done for beams of complex treatment plan and isocenter QA. Results: The Cherenkov image widths matched with the measured GaF images and light field images, with accuracy in the range of ±1 mm standard deviation. The differences between the measurements were minor and within tolerance of geometrical requirement of standard linac QA procedures conducted by human setup verification, which had a similar error range. The measurement made by the remote imaging system allowed for beam shape extraction of radiation fields at the SSD location of the beam. Conclusions: The proposed Cherenkov image acquisition system provides a valid way to remotely confirm radiation field sizes and provides similar information to that obtained from the linac light field or GaF film estimates of the beam size. The major benefit of this approach is that with a fixed installation of the camera, testing could be done completely under software control with automated image analysis, potentially simplifying conventional QA procedures with appropriate calibration of boundary definitions, and the natural extension to capturing dynamic treatment beamlets at SSD could have future value, such as verification of beam plans with complex beam shapes, like IMRT or "star‐shot" QA for the isocenter. [ABSTRACT FROM AUTHOR]

Objective: To test if Raman spectroscopy (RS) is an appropriate tool for the diagnosis and possibly grading of prostate cancer (PCa). Patients and Methods: Between 20 and 50 Raman spectra were acquired from 32 fresh and non‐processed post‐prostatectomy specimens using a macroscopic handheld RS probe. Each measured area was characterized and categorized according to histopathological criteria: tissue type (extraprostatic or prostatic); tissue malignancy (benign or malignant); cancer grade (Grade Groups [GGs] 1–5); and tissue glandular level. The data were analysed using machine‐learning classification with neural network. Results: The RS technique was able to distinguish prostate from extraprostatic tissue with a sensitivity of 82% and a specificity of 83% and benign from malignant tissue with a sensitivity of 87% and a specificity of 86%. In an exploratory fashion, RS differentiated benign from GG1 in 726/801 spectra (91%; sensitivity 80%, specificity 91%), from GG2 in 588/805 spectra (73%; sensitivity 76%, specificity 73%), from GG3 in 670/797 spectra (84%; sensitivity 86%, specificity 84%), from GG4 in 711/802 spectra (88%; sensitivity 77%, specificity 89%) and from GG5 in 729/818 spectra (89%; sensitivity 90%, specificity 89%). Conclusion: Current diagnostic approaches of PCa using needle biopsies have suboptimal cancer detection rates and a significant risk of infection. Standard non‐targeted random sampling results in false‐negative biopsies in 15–30% of patients, which affects clinical management. RS, a non‐destructive tissue interrogation technique providing vibrational molecular information, resolved the highly complex architecture of the prostate and detect cancer with high accuracy using a fibre optic probe to interrogate radical prostatectomy (RP) specimens from 32 patients (947 spectra). This proof‐of‐principle paves the way for the development of in vivo tumour targeting spectroscopy tools for informed biopsy collection to address the clinical need for accurate PCa diagnosis and possibly to improve surgical resection during RP as a complement to histopathological analysis. [ABSTRACT FROM AUTHOR]

Two trypsin inhibitors from the seed or Acacia elata, a legume of the subfamily Mimosoideae, were isolated by affinity chromatography on trypsin-Sepharose 48 and separated by chromatography on SP-Sephadex C-25 and Sephadex G-100. The two inhibitors, with molecular weights of about 20000, were composed of two polypeptide chains linked by a disulfide bond. The two inhibitors had essentially the same amino acid compositions and both contained four half-cystine residues, no methionine and were rich in aspartic acid, glutamic acid, glycine and leucine. The inhibitors had isoelectric points of 6.4 and 5.9. The inhibitors stoichiometrically inhibited trypsin in the molar ratio of 1: 1, α-chymotrypsin was inhibited also in a 1: 1 molar ratio but the binding of the enzyme by the inhibitor was weaker and the inhibitor-chymotrypsin complex dissociated during the assay. Both enzymes are probably inhibited at an identical site. Amino-terminal sequence analysis of the two polypeptide chains of the inhibitors revealed extensive homology with the trypsin inhibitor from the silk tree (another Mimosoideae legume); both these inhibitors are homologous with the soybean trypsin inhibitor (Kunitz). [ABSTRACT FROM AUTHOR]